1. Field of the Invention
The present invention generally relates to amorphous poly-alpha-olefin (APAO) hot melt adhesives. More particularly, it relates to improving the performance of amorphous poly-alpha-olefin hot melt adhesives for use in all industrial adhesive applications including, but not limited to, assembly, construction, lamination, footwear and automotive components, by blending with a low molecular weight, functionalized, isotactic polypropylene.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
U.S. Pat. No. 7,262,251 to Kanderski et al. describes a hot melt adhesive composition that is based on an isotactic polypropylene random copolymer. The composition contains about 4%-50% by weight of the random copolymer, about 20%-65% by weight of a compatible tackifier, about 0%-40% by weight of a plasticizer, about 0%-3% by weight of a stabilizer, about 0%-40% by weight of a wax, about 0%-60% by weight of an atactic poly-alpha-olefin (APAO), and about 0%-40% by weight of a secondary polymer.
U.S. Pat. No. 7,786,032 to Zhou et al. describes adhesive compositions comprising selected ratios of crystalline and amorphous polymers. In some versions, polymers capable of existing in different configurations (e.g., a polymer such as polypropylene which may exist in an atactic, syndiotactic, or isotactic configuration) are used to prepare adhesives. As an example, a selected amount of isotactic polypropylene is blended with a selected amount of atactic polypropylene to prepare an adhesive composition having one or more performance properties (e.g., bond strength) that are said to be superior to the performance properties of a conventional hot-melt adhesive.
U.S. Pat. No. 5,302,675, entitled “High Tensile Strength Amorphous 1-Butene/propylene Copolymers”, describes a process for the production of high tensile strength 1-butene/propylene copolymers by reacting 1-butene and propylene monomers in the presence of a catalyst system comprising a) a solid supported catalyst component of the type commonly known as a Ziegler-Natta coordination polymerization catalyst, b) a trialkylaluminum cocatalyst component and c) and an organo alkoxy silane component commonly referred to in the polyolefins industry as an external electron donor, or external donor. The butene-1/propylene copolymers have substantially improved mechanical and rheological properties which make them desirable for use in such applications as hot melt adhesives, sealants, coatings and similar applications.